1. Field of the Invention
This invention relates to devices used in vehicular internal combustion engines and specifically, to efficient control and use of crankcase fumes.
2. Prior Art
Automobile engines contribute to atmospheric pollution by spewing forth unburned or partially burned gaseous hydrocarbons and even droplets of unburned oil. A principal offender in this respect are the fumes which originate in the crankcase and which in the past, were allowed to escape to the atmosphere. In recent years, laws have been passed which require the fumes to be channeled back to the air intake manifold of the engine, there to be mixed with the incoming fuel-air mixture so that the unburned hydrocarbons in the fumes will be burned in the engine cylinders.
In existing automobile engines, a crankcase ventilation conduit has its intake end usually located upstream of the carburetor in such manner as to pass fresh air into the crankcase. Ventilation of the crankcase is achieved by drawing off this air and entrained fumes, gases, etc., through a conduit connected to the downstream side of the carburetor or to the air intake manifold.
The crankcase fumes and ventilating air pass into the induction system downstream of the carburetor. Because of this, the flow from the crankcase to the intake manifold must be controlled. To provide such control, a pollution control valve, or positive crankcase ventilation valve (PCV valve) is located in the conduit connecting the crankcase to the engine air intake manifold. The PCV valve closes during engine idling when the vacuum in the intake manifold is high. When the PCV valve is closed, the ventilating air and fumes either are blocked off entirely or only small amounts are allowed to pass through an orifice in the PCV valve member.
As the engine speeds up, the PCV valve opens to permit larger quantities of air and crankcase fumes to be drawn into the intake manifold, thus increasing the ventilation effect in the crankcase. The PCV valve operates in a puttering manner, rather than smoothly fully opening and closing. While PCV valves are quite effective in obtaining less ventilation when the engine is idling and more ventilation when the engine is speeded up, the minimal flow through the PCV valve during idling adversely affects engine idling and increases gasoline consumption. The design of the PCV valve is a compromise between good idling and effective burning of the crankcase fumes.
In engines which are not provided with a PCV valve, it is still desirable to increase the air flow into the intake manifold downstream of the carburetor, except when the vehicle is idling and the intake manifold vacuum is high. An additional supply of air reduces the amount of vaporized fuel that is drawn through the carburetor and that would be wasted in the vehicle exhaust and would pollute the environment. The richness of the fuel air mixture is preferably reduced. A more correct air to fuel ratio is assured.
In a vehicle having a PCV valve, the device of the present invention is designed for being positioned in the conduit leading from the PCV valve to the downstream side or base of the carburetor. The device acts to permit improved idling characteristics and reduce fuel consumption. In a vehicle engine that pipes crankcase fumes through a PCV valve back to the intake manifold, often there is insufficient oxygen for complete combustion of the gasoline plus the unburned combustible hydrocarbons in the crankcase fumes. The device of the invention helps supply that needed oxygen and also breaks up the unburned hydrocarbons to facilitate their combustion. There are many devices which attempt to solve this problem. Such a device of this general type is disclosed in U.S. Pat. No. 3,809,035, and U.S. Pat. No. 3,923,024, among others.
The prior art devices basically comprise a spring loaded ball check valve which is adapted to close when the PCV valve is closed and minimum fumes are being admitted to the intake manifold. The ball check valve opens when the PCV valve is open and increased fumes and unburned hydrocarbons are passing through the conduit to the intake manifold.
The typical example is U.S. Pat. No. 3,923,024. There, the ball check valve as in other prior art devices blocks the entrance of ambient air into the ventilation passage. "At acceleration, at high engine speed and also when the engine is under load such as lugging up a grade . . . ." The spring 26 is designed to force the ball check valve away from the seat when the force in the spring exceeds the downward force of the vacuum. In theory, such cooperative action between the spring and ball check valve sounds functional. In reality, the prior art system for activating the ball check valve is totally ineffective for the following reasons:
(1) Amount of vacuum required to cause ball valve to move down must be greater than that amount to hold it down, hence, the valve does not operate at optimum levels since it is designed for less than optimum conditions; PA1 (2) The spring is difficult to form as a mass production item having precise compressive strength; PA1 (3) Puttering effect of PCV valve causes the vacuum to change rapidly which increase its ineffectiveness because of non-use at optimum vacuum levels; PA1 (4) It operates under all demand load situations. The above reasons all not only show theoretical but mechanical deficiencies of the prior art devices. Additionally, however, the major problem is that the ball check valve is designed to operate under all load conditions or demand situations. Operation as accomplished in the prior art leans the fuel mixture when it should not. It needs to be pointed out that the gas lubricates the valves and if the fuel mixture is leaned too much under load conditions, valves may get burned. Burning of valves has become a problem of vehicles using the devices of the prior art.
The present invention overcomes these problems by creating a device which does not depend on the vacuum system to operate, yet provides all of the other beneficial effects of the prior art devices.